Electrical precipitator



Jan. 6; 1931. c. z. ROSECRANS 1,787,955

ELECTRICAL PRECIPITATOR Filed June 26, 1929 Patented Jan. 6, 1931. v

cannu a. zikosncnms,

a nominee courm, or PENNSYLVANIA,

or rnmanurnn, rxnnsynvmm, AssIoNon' 'ro LEEDS PHILADELPHIA, PENNSYLVANIA, a oonronurrox or ELECTRICAL rimcrrrra'ron Application filed June as. 1929. mm n). 313,805.

My invention relates to the electrical precipitation pf finely divided particles of matter, as of vapor, from as, and particularly from a. gaseous stream owing, for example,

to analyzin apparatus.

My invezion resides in a precipitator of improved co struction particularly suited for use with a source of unrectified alternating current ofhi h potential, and more specificallo ly, itcompri es-a tubular electrode member, through which the stream of gas or vapor passes, supported by a metal chamber, preferably ground mechanically and electrically connected to the metal supporting structure or chamber.

My invention further resides in the methods, system and features of construction and arrangement hereinafter described and claimed.

For an illustration of one of the forms my invention may take, reference is to be had to the accompanying drawing:

. At its lower end the tubular member 1, is providedwith a gas inlet 2 and at its upper end with a gas outlet 3. Disposed upon the exterior of the tube between the gas inlet and outlet is an electrode 4, preferably of metal foil or other conductive coating to insure intimate contact between theadjacent faces of the electrode and tube. Theinner electrode 5 preferably a fine wire of suitable material, as platinum, is supported at the upper end of the tube by a plug 6 of suitable insulating material as glass, and extends substantially axially of the tube, the lower end thereof be ingheld by an electrically conductive supporting member 7 projecting-inwardly from a collecting chamber 8, which may be of metal, as iron.

The open upper end of the chamber 8 is threaded to receive a plug 9 through which the open, lower end of tube 1 extends, a sealing ring 10, of heavy packing material, preferably impregnated with grease, for example, closing the chamber to,atmosphere. From .the lower end of the chamber 8 there extends a pipe 11 having a U bend in which liquid 12 collects providing a trap or seal.

ed to the secondary 13 a commercial power source of ed, with a wire-like electrode extending axially of the tubular electrode and 390,351, filedQct. 9, 1928,

The electrodes 4 and 5 are directly connectof a-step-up transformer 14 whose primary 15 is connected to ordinary frequency and voltage, for example, a 60 cycle- 110 volt line. It is desirable to ground one of the electrodes and I prefer, to ground the inner electrode 5 by a connection from the metal structure of the chamber 8 to earth E.

It is characteristic of myinvention that-the precipitator electrodes are directly connected to a source of unrectified alternating current, the electrostatic field between the electrodes reversing at line frequency. .To attain efiicient precipitation withthis circuit arrangement, the precipitator' is so constructed that the charged mist particles travel across the gas stream into contact with a collecting surface, as the electrode 5, or the inside of tube 1, before reversal of polarity of the electrodes. In the specific type of apparatus shown, the distance between the electrodes 4 and 5 is so small that charged particles in the stream traverse the distance between their original position to a collecting surface, that is either to wire 5, or the inside of tube 1, during the time of one-half. cycle. When the frequency of the impressed voltage is 60 cycles, and potential of or about 15,000 volts impressed upon the electrodes,a tube of about threequarter inch inside diameter is suitable. The length of electrode 4 and consequently of the v region 1n which the gas stream is subjected to the action of an electric-field is sufficiently great to insure substantially complete precipitation, for example to within .1 per cent. The tube 1 is preferably of lead glass or other semi-conductive material lo obtain large potential drop between the electrode 5 and the interior. surface of the tube. In effect the tube 1 adjacent the metalfoil 4 is, itself an electrode, the glass conducting appreciable current at the high potentials-involved. To avoid excessive losses, the length of tube 1 from the edges of outer electrode4 to the nearest conductorof opposite polarity is suitably great. 2 v co-pending application Serial No. there is described In my a system in which the precipitator is utilized 3. An electrical precipitator com rising an to remove 80,, or sulphuric acid mist, from insulating tube, a wireike electrode extenda stream of S ing axially thereof, a conductive coating on From a gasstream whose SO content is to sald tube, ametal chamber receiving the lower 5 be determined, there is drawn by suction a end ofsaid tube and substantiall spaced from 76 continuous sample which passes through inlet said coating thereon, means mec anically and 2, upwardly through precipitator tube 1, and electrically connecting the lower end of said outwardly through outlet 3 to suitable SO wire-like electrode to said metal chamber, analyzing apparatus. As the gas stream means for producing an electric difl'erence of pa upwardly through tube 1, the sulphuric potential between said wire-like electrode and acid mist particles collect upon the electrode said conductive coating, and fluid'inlet and 5 and 011 the inner surface of tube 1, and run outlet conduits opening into said tube on opdown into the chamber 8. The acid drain leg osite sides of said conductive coating, wherecomprised o-f-the tube 11 is dimensioned so by fluid passing th rbiigh the tube traverses 15 that a liquid seal at the U-sha ed bend 16 is the field between sald coating and said wiremaintained with the desired su -atmospheric like electrode. pressure within chamber 8; forexam le, the 4. An electrical precipitator comprising a pressure in chamber 8 maybe 25 0 water tubular electrode, a wire-like electrode exbelow atmospheric. During operation, the tending axially thereof, a closed metal chamo liquid drips from the lower opening of the her supporting said tubular electrode and in pipe as the acid collects in chamber 8. communication with the interior thereof, a If it is desired to ascertain the proportion fluid inlet conduit opening into said tubular of sulphuric acid mist, a definite volume must electrode above said chamber, a fluid outlet be passed through the piecipitator, the preopening into said tubular electrode more re- 35 cipitate Washed, and a titration made. To 111- mote from said chamber than said inlet,-and o crease the precipithting capacity, particularmeans mechanically and electrically connects 1y for purposes other than analysis which reing the lowerend of said wire-like electrode quire larger volumes or ua'ntity of gas, a to said metal chamber, and means for prosuitable number of precipitators may be ar ducing an electric diflerence of potential beso ranged in multi le. tween said electrodes, the fluid stream passing hile I have escribed my precipitator as through the field between said electrodes in being utilized to remove articles of mist flowing from inlet to outlet. from the gas stream, it will e understood the CRA'NDALL Z. ROSECRAN S. particles may be of a finely divided solid.

a5 lfurther it will be appreciated that my inven- 10c,

t1on is not limited to the specific construction shown, but is of breadth commensurate with the scope of the appended claims.

I claim; q) 1. An electric precipitator comprising'n tube of semi-conductive material, a conductive coatin on the exterlor and intermediate the ends thereof, a wire electrode, metallicstructure supporting said electrode and said u tube substantially spaced from said conduc-- i n tive coating, and means connecting said me, tallic structure and said wire electrode to earth, means for producing an electric difference of potential between said coating and r so said wire electrode, and means for directing a stream containing finely divided particles, to one end of said tube for passage through d the electric field therein.

2. An electrical precipitator comprising a as tubular electrode, awire-like electrode ex- ,1

lending axially thereof, metal structure supporting said tubular electrode and insulated ducing an electric difference of-potentla tween said electrodes, and means for directin a stream containing finely divided partic es to the electric field between said elec- 86 trodes. no 

